1. Field of the Invention
The invention relates to the field of cellular telephone equipment and in particular to solar powered telephone call boxes using a cellular telephone system to radiotelephonically communicate from a plurality of fixed roadside sites.
2. Description of the Prior Art
Emergency roadside call boxes have become increasingly important and productive elements in providing roadside security and emergency assistance in the metropolitan areas in the United States and throughout the world. Originally, such roadside emergency call boxes were hardwired to conventional telephone land lines. However, the installation of such telephone land lines substantially escalates the installation and maintenance costs of such emergency roadside telephone boxes. In order to overcome this limitation, the prior art devised emergency telephone call boxes which use a radio transmission link for communications. Cannalty et al., "Emergency Communications System", U.S. Pat. No. 3,939,417; and Wisniewski, "Emergency Calling System", U.S. Pat. No. 3,492,581 show such systems. Power for the these call boxes is provided by a rechargeable battery included within their housings. However, such prior art battery operated systems either required the units to be coupled to a source of electrical power for trickle-charging or required the periodic replacement or recharging of the battery packs through mobile roadside service. Again, although savings were realized in installation costs by using battery powered units, the maintenance or service costs of such systems often prohibited their use.
Furthermore, in the past radiotelephone communications within geographic areas were realized using a process based on a single transmitter and antenna. This method of communication limits the number of calls that can be placed in a geographic area and limits the size of the area that can be covered with a given amount of equipment. However, with the recent advent of cellular telephone technology, these limitations, which were characteristic of the prior art single transmitter systems, no longer exist.
Therefore, what is needed is a design and method of using a radio linked emergency call box which is adaptable to cellular telephone technology and which is characterized by low installation and service costs.